The present invention relates generally to ring laser gyros and, more particularly to a ring laser gyro including at least one ion trap outside of the gas discharge path.
It is known, for example, from German Patent No. DE-OS 28 39 066 with respect to a triangular-shaped laser block to arrange, symmetrically to the center line of the triangular block, at each side leg an anode and at the base leg of the triangular block a cathode. By applying an ignition voltage between the anodes and the cathode ionization of the gas is achieved and a gas discharge is ignited so that two counter-propagating laser beams are generated within the triangular-shaped resonator path. The ignition voltage of the gas discharge depends on the shape and the length of the discharge path and also on the gas pressure and the gas composition. When the gas discharge has been started, then the inner resistance of the discharge path is decreased and the voltage between the anode and the cathode is reduced to the burning voltage. In gas discharges having two partial discharge paths as, for example, in a ring laser gyro, both paths do not ignite at the same time. In such cases a situation arises wherein one electrode is still on the ignition voltage whereas between the two other electrodes only a potential difference exists according to the burning voltage. Since the ignition voltage is remarkably higher than the burning voltage the possibility arises that the discharge is ignited in the resonating bore which does not belong to the amplifying bore. This situation must be prevented and, therefore, measures have already been taken within the ignition electronics by which the discharge is switched-off in the event where the voltage values at the electrodes after the ignition ar not symmetrical. Afterwards an ignition operation is again started. This measure does not solve the basic problem since the discharge in both paths basically cannot be started at the same time.